Expansible pile driving mandrel



Jan. 21, 1964 w. H. coBI 3,118,284

EXPANSIBLE PILE DRIVING MANDREL.

Filed Nov. 24, 1961 2 Sheets-Sheet l Jan. 21, 1964 w. H. coBl 3,118,284

EXPANSIBLE PILE DRIVING MANDREL Filed Nov. 24, 1961 2 Sheets-Sheet 2 y L l' M if f Weil n' I Il. i l l SEB- +P 64 l N T 48* I Il +ril 48' `T. T M t 7 United States Patent O 3,118,284 EXFANSBLE PELE DPJVBNG MANDREL Waiter i-i. Cobi, North St., Greenwich, onn.; dames G. Hoiiand and Siivn K. Cohi, executors o said Waiter H. ohi, deceased Fiied Nov. 24, 196i, Ser. No. 154,554 8 Claims. (Ci. 61 53.72)

This invention relates to mandrels for driving piles and, more particularly, to mandrels for driving thin Walled pile shells.

vlt is often the practice, in foundation piling, to drive a relatively light gauge shell and, after the shell has been driven to the proper strata, lill the shell with concrete. Such piles are generally referred to as cast-in-place piles.

The shell driven in this type of piling is a tubular, cylindrical container and is usually provided with corrugations which extend spirally along the container wall. ln most instances, it is the practice to close one end of the shell with a cap or boot and drive the shell from its open end.

The shell is driven with a hammer or other driving means. While sufficiently strong to stand open to receive concrete yafter it is driven, the shell does not have sufficient strength to withstand driving forces. lt is, therefore, the practice to drive such shells with a mandrel. Such mandrels are inserted in the shell before driving and usudly extend from the bottom or closed end of the shell upward beyond the upper or open end. At its upper end, the mandrel is connected to a bonnet, -which connects the mandrel to the hammer or other means which may be employed to drive the mandrel and shell.

Gne type of mandrel, used extensively for this purpose, employs a plurality of movable segments. These segments have arcuate surfaces for engaging the shell wall and extend axially along the mandrel, at least for substantially the full length of the shell. Ribs or bars are provided along the outer surface of the segments to engage the corrugat'ons or" the shell. in order to inser the mandrell into Iand Withdraw the mandrel from the shell, the arcuate segments move radially with respect to the axis of the mandrel. To insert the mandrel into the shell for driving and to remove the mandrel from the shell after driving, the segments are moved radially inward toward the mandrel axis and out of engagement with the shell walls. When the mandrel is in position in the shell, the segments are moved radially outward into engagement with the inner Wall of the shell, the ribs or bars on the segments engaging in the corrugations of the shell wall, locking the shell to the mandrel. During driving, the driving force is imparted to the top of the mandrel and the mandrel land shell are driven as a unit into the ground. The arcuate segments, in addition to transmitting the driving force to the shell, support and reinforce the shell walls.

ln mandrels commonly used heretofore, each segment is, for practical purposes, `an independent driving unit, that is, the driving force is applied to the top of each segment. The segments lare moved into and out of engagement with the inner walls of the shell in many ways. ln some mandrels this is accomplished mechanically and, in others, hydraulically or pneumatically. The actuator may be double acting, that is, in one direction of movement of the actuator the segments are moved into engagement with the shell and in the other direction, out of engagement. The actuator may also be single acting, in which event the segments are usually moved into engagement by the actuator and withdrawn with springs connected to the segments on rods which pass through the segments. In either event, either through mechanical connection between the segments and the actuator or in "ice 2 some other manner, for example, rods or pins passing through the segments, means must be provided to maintain alignment between the otherwise independent segments.

irrespective oi the means employed, it is often diilicult to maintain the segments in alignment in the shell. During driving an obstruction, such as a boulder, buried concrete slab, tree trunk or the like, is often encountered. These might become lodged against one side of the shell, substantially increasing the driving resistance on one mandrel segment without appreciably affecting the resistance on the other segment. With the driving resistance out of balance, the driving impact imparted to the mandrel tends to drive one segment further than lthe other segment. This difference in driving can, and often does, misalign the segments land damage the shell. Damage to the mandrel may also occur, the repair of which may require complete replacement of `the alignment means.

While damage to the alignment mechanism is not uncommon when driving shells vertically, this problem is even more pronounced when shells are driven at an angle. When driving shells at an angle Ifor what is commonly known as batter piles, it is exceedingly diicult to maintain the hammer at the proper driving angle with the mandrel. Thus, the hammer tends to drive one segment harder than the other. This often causes damage to the sheil and mandrel. in many instances, both with vertically driven piles and batter piles, when the alignment means is damaged, the segments are frozen into engagement 'with the shell. If this occurs, the shell and mandrel must be pulled out of the `ground and the shell cut trom the mandrel. Such an operation is both time-consuming and expensive.

It is an object of the present invention to provide an improved pile driving mandrel.

A further object is to provide such a mandrel in which the mandrel segments are intixed alignment.

A still further object of the invention is yto provide a unitary mandrel in which the driving forces are imparted uniformly to the mandrel segments irrespective of alignment between the driving means and the mandrel.

Still a further object of the invention is to eliminate the alignment mechanism between the segments.

These and other objects of the invention will be apparent from the description and accompanying drawings, in which:

FIG. l is a longitudinal and broken sectional view of the device of the invention showing the mandrel segments in engagement with a shell;

FiG. 2 is a transverse sectional view taken along the line 2 2 of FIG. l;

FIG. 3 is a transverse sectional View taken along the line 3 3 of FIG. l;

FIG. 4 is a transverse sectional view taken along the line 4- 4 of FIG. l;

FiG. 5 is a transverse sectional view taken `along the line 5 5 of FIG. l;

yFlGr. 6 is a transverse sectional View showing one of the actuators of the device with the mandrel segments in their expanded or shell engaging position;

FIG. 7 is a transverse sectional view similar to FIG. 6 but showing the segments in their contracted or disengaged position;

PEG. 8 is a longitudinal sectional View of the actautor taken along the line `3 8 of FIG. 6; and

FG. 9 is a longitudinal sectional view of the actuator taken along the line 9 9 of FIG. 7.

ln the following description, the invention is described in connection with a mandrel in which the segments are actuated into engagement with the shell by a mechanical actuator operated by a hydraulic cylinder and piston. It is to be understood, however, that the mechanical actuator may be operated by air or by a mechanical mechanism and that, if desired, the segments may be operated directly by pneumatic or hydraulic actuators or by combinations thereof. For example, a pneumatic actuator of the type shown in U.S. Patent 2,990,688 may be employed as may the actuator shown and described in my copending application ,Serial No. 17,037, tiled March 23, i960, now Patent No. 3,064,439.

In the mandrel of the instant invention the mandrel segments are joined or interconnected at their upper end into a composite, unitarX head. The hammer is connected to the upper end of the composite head and the radially movable portion or the segments extends axially downward therefrom. While iixed or joined at their upper ends, the lower ends, and substantially the full length of the segments, are free for radial movement with respect to the mandrel axis.

TheV segments may be fixed at their upper ends in either their normal expanded position or their normal contracted position, in either event, the lower ends of the segments, that is, the ends'of the segments at the bottom or closed end ot' the shell, are movable radially with respect to the mandrel axis to engage and disengage the segments with the inner wall of the shell.

Whether lixed in expanded position or contracted position, when the mandrel is engaged in the shell, trie shell wall is engaged for a considerable portion of its length. Itv is obvious, when the segments are fixed to the head in their expanded position, the length of the segments in engagement with the walls of the shell will be in contact along a greater axial length than when the segments are xed in their contracted position. However, under most driving conditions, sufficient Contact between the segments and' shell can be attained even with the upper end of the segments iixed in their contracted position.

The mandrel segments, in their free aea below and away from their xed mounting on the head, may be set to engage the inner shell wall without the use of an actuator or may be set out of engagement with the shell wall. If set to engage the shell wallrneans must be provided to move the segments radially inward out of contact with the' wall in order to insert the mandrel into and remove the mandrel irom the shell. Where thesegments are set out of engagement, an actuator must be provided to move the segments radially outward to engage the shell. In either event, during driving, it is preferred to reinforce or loca the mandrel segments into engagement with the shell.

Referring now to the attached drawings showing the invention as applied'to a mandrel with the upper end oi the, segments attached in fixed expanded position, in FiG. l there is shown head 2 having, at its upper end, flange 4 connected through yoke 6 to bonnet 8. Bonnet S connects head 2 and the mandrel to the driving means which, for purposes` oi illustration, is'shown generally at itl as the piston of the hammer.

AtA its lower end, head 2 has ange i2 connected by bolts 14 to ilanges 16, 1S on mandrel segments indicated generally 2l), 22. A cylindricalbore 24 extends axially into head 2 upward from the lower end of the head, bore Zaihaving a liner 26. At-its upper and lower ends bore 24 is connected by passage 28, 3@ and hoses 32, 345 to a -suitable pressure source otV hydraulic fluid, not shown. A'piston 36, connected at one of its sides to actuator rod 3S, is positioned inV bore 24 and liner 26. At its lower end VboreZffi-is provided with a seal all.

Mandrel segments 2l); Zare identical and, for purposes of brevity, only one segment will be described. Each mandrel segment consists of an upper arcuate body d2, a lower arcuate bodyl 44 and intermediate arcuate bodies 46, the bodies being joined or interconnected by outer arcuate plates 48 and-inner plates Si). Bodies 42, 44, 46 may be cast, forged or formed in any suitable mannerV and are joined to plates 53, 5i? by welding or similar means. Rods or bars 52 are attached to the outer surface of plates 48, the rods or bars being positioned and angu- L: larly attached to plate i8 to engage in the corrugations of the wall of shell 49 when the mandrel is in its expanded" position, as shown in FIG. l'. For reasons which will be more apparent hereinafter, it is preferred to omit the corrugation engaging bars 52 at the upper end of the mandrel segments.

Referring particularly to FGS. 6 to 9, plates 54, 56 are mounted, by welding or in a similar manner, to the inner face of plate 5?. Plates S4, 56 are spaced on opposite sides of the center line oi plate 5? and extend axially of the segment. A pin extends transversely through plates 54, 56 and is held in position in the plates by clips 69, 62; Pins 5S may be heldin lixedY position in plates 54, So; or preferably, may rotate on their'axes in the plates.

Actuator rod 3S extends downward from head 2 intermediate segments Ztl, 22 and is provided, at spaced points, with tapered camming members 64, camming members d'being ixedto rod 3S and being positioned on the rod adjacent opposing pins 53 on segments 2li, Z2, respectively.

Asbest shown in FIGS. 4 and 5, the opposing arcuate bodies de' of segments 2i), 22 are provided with aligned bores 7i?, 72 counter-bored at'i, 75 to re eive springs 73, Sti, respectively. A' spring bolt 2 passes through bores 7i?, 72 and springs 78, 8l) and is provided, at its opposite ends, with spring seat washers Sd and nuts 36. With the mandrel segments 2t?, 22 expanded, springs 73 are under compression.

In the embodiment illustrated, segments 2i), 22 are iixcd to'head 2 in` their expanded position. When piston 36 is moved downward, actuating rod 3S and camming members 6d' are moved' downward. As carnming members-e4 move downward, springs 78, under compression, rorce segments Ztl, 2.2 to move inwardly toward the axis of the mandrel, collapsing or retractingl the mandrel and' retracting bars 52 out of the shell corrugations. With the segments retracted and bars` 52 out of the corrugations, themandrel can be removed from the shell or a shell can be inserted on the mandrel.

To expand the mandrel, piston ti'is moved upward by admitting luid, underv pressure, through passage 30 and hose 3d into the lower end of bore 2d. As piston 36 moves upwardly, actuator rod 3S and camming members4 efi'move upward, camming'members 64, through ContactV with opposing pins 53, forcing segments 2t), 2,2 outward into engagement with the shell wall. As segments Ztl, 22 move outward, springs 7S are compressed. The mandrel is now in driving position in the shell. ln addition to moving segments Ztl, 22* outward and compressing springs ''camming members 64, when the mandrel is in driving position, reinforces the" segments during driving.

As has been noted hereinabove, the upper end of segments 2%, 22 are joined in xed position. Thus, no radial movement occurs at the head when the mandrel is expanded or contracted. Such movement is limited to those portions of the segments which are free and extend into the shell. Although the segments are relatively rigid, they are sufficiently flexible to permit the segments to be deflected. Since the only interconnection between the segments and the shell, when the mandrel is expanded, is the projection of the bars 52 into the shell corr'ugations, only a relatively small amount of contraction or deiiection is required to removeV the shell from the mandrel.

ln driving shells with the mandrel of the instant invention, the top or upper ends of the segments are iixed or joined asa single, composite unit. The driving forces are applied to the composite unit and are then transmitted to the shell through the movable portion of the segments. Any misalignment in the application of the driving force to the upper end of the mandrel is absorbed in the composite -unit and the forces are transmitted substantially equally to the lower or expansible portions of thel segments. Conversely, should driving resistance on one segment be increased by an obstruction or for some other reason, the resistance is transmitted to the composite unit and to the other mandrel segment.

The terms and expressions which have been employed are used as terms of description and not of limitation, and there is no intention, in the use of such terms and expressions, of excluding any equivalents of the features shown and described or portions thereof, but it is recognized that various modifications are possible within the scope of the invention claimed.

What is claimed is:

1. A mandrel for driving pile shells comprising a plurality of continuous segments extending longitudinally along the driving axis of said mandrel, said segments having outer surfaces for engaging the inner wall of a pile shell and being rigidly interconnected and joined at their upper ends in fixed position relative to each other and to the driving axis of said mandrel forming a rigid, composite head for receiving driving impacts to drive said segments as an integrated unit along said axis, each of said segments extending downward from said rigid, composite head independently and freely of the other of said segments, said downward extending segments being dis- 1 csed in opposed positions for ilexural movement beneath said head relative to each other and to said axis, and actuating means intermediate said segments for ilexing said segments beneath said rigid head into and out of engagement with a shell in a path transverse to the driving axis ot said mandrel.

2. A mandrel as recited in claim 1 in which said actuating means includes a first means for moving said segments in a iirst direction transverse to said axis and a second means -for moving said segments in a direction opposite to said iirst direction.

3. A mandrel for driving pile shells comprising a plurality of continuous segments extending longitudinally along the driving axis of said mandrel, said segments being rigidly interconnected and joined to each other at their upper ends in ixed position relative to each other and to the driving axis of said mandrel forming a rigid, con posite head for receiving driving impacts to drive said segments as an integral unit along axis, each of said segments extending downward from said rigid, composite head independently and freely of each other, said downward extending segments having outer surfaces for engaging the inner wall of a pile shell and being disposed in opposed positions along said driving axis for flexural movement beneath said head relative to each other and to said axis, and actuating means intermediate said segments for exing said segments beneath said rigid head into and out of engagement with a shell in a path transverse to the driving axis of said mandrel.

4. A mandrel for driving corrugated pile shells comprising a plurality of continuous segments extending axially along the driving axis of said mandrel, said segments being rigidly interconnected and joined to each other at their upper ends in tixed position relative to each other and to the driving axis of said mandrel forming a rigid, composite head for receiving driving impacts to drive said segments as an integral unit along said driving axis, each of said segments extending downward from said rigid, composite head independently and freely of each other, said downward extending segments having outer surfaces for engaging the inner wall of a pile shell and being disposed in opposed positions along said driving axis for tlexura-l movement beneath said head relative to each other and to said axis, means on said outer surfaces of said segments for engagement in the corrugations of a pile shell, and actuating means intermediate said segments for lexing said segments beneath said rigid head into and out ot engagement with a shell in a path transverse to the drivingaxis of said mandrel.

5. .A mandrel for driving pile shells comprising a plurality of continuous segments extending axially along the driving axis or said mandrel, said segments being rigidly interconnected and joined to each other at their upper ends in fixed position relative to each other and to the driving axis of said mandrel forming a rigid, composite head for receiving driving impacts to drive sc id segments as an integral unit along said axis, each of said segments extending downward from said rigid compact head independently and freely of each other, said downward extending segments being liexible and having outer surfaces for engaging the inner wall of a pile shell and being disposed in opposed positions along said driving axis for flexural movement beneath said head relative to each other and to said driving axis, means in engagement with opposed segments for moving said segments inwardly toward the of said mandrel to disengage the outer surfaces or said segments and the inner wall of a pile shell, and actuating means for engaging with said opposed segments for flexing said downward extending semnents outwardly away from the driving axis oi said mandrel for engaging said outer surfaces with the inner wall of a pile shell.

6. `in a mandrel as recited in claim 5 in which said means for moving said segments inwardly is spring means connected to said opposed segments.

7. A mandrel for driving pile shells comprising a plurality of continuous segments extending axially along the driving axis of said mandrel, said segments being rigidly joined and interconnected to each ot -er at their upper ends in fixed position relative to each other and to the driving axis of said mandrel forming a rigid, composite head for receiving driving impacts to drive said segments as an integral unit along said axis, each of said segments extending downward `from said rigid, composite head independently and ire-ely of each other, said downward exte. ding segments being iiexible and having outer surfaces engageable with the inner wall of a pile shell lwhen said mandrel is positioned in a shell, and actuating means intermediate said downward extending segments for iiexing said segments in a path transverse to the driving axis of said mandrel to engage said outer surfaces of said segments with the inner wall of a shell.

8. in a mandrel as recited in claim 7 in which said actuating means comprises an actuating rod extending axially of said mandrel intermediate said segments, cam means on said actuating rod, camming pins on said segments disposed in opposed positions thereon, and means for moving said actuating rod and said cam means into engagement with said camming pins to move said segments outward to engage the outer surface ot opposed segments with the inner wall or said shell.

References Cited in tl e tile of this patent UNITED STATES PATENTS 1,865,6'3 Upson et al July 5, 1932 2,625,015 Cobi ian. 13, 1953 2,871,666 yPickman Feb. 3, 1959 FOREGN PATENTS 225,290 Great Britain Dec. 1, 1924 1,068,366 France Feb. 3, 1954 728,211 Great Britain Apr. 13, 1955 81,0118 Norway Mar. 15, 1956 

1. A MANDREL FOR DRIVING PILE SHELLS COMPRISING A PLURALITY OF CONTINUOUS SEGMENTS EXTENDING LONGITUDINALLY ALONG THE DRIVING AXIS OF SAID MANDREL, SAID SEGMENTS HAVING OUTER SURFACES FOR ENGAGING THE INNER WALL OF A PILE SHELL AND BEING RIGIDLY INTERCONNECTED AND JOINED AT THEIR UPPER ENDS IN FIXED POSITION RELATIVE TO EACH OTHER AND TO THE DRIVING AXIS OF SAID MANDREL FORMING A RIGID, COMPOSITE HEAD FOR RECEIVING DRIVING IMPACTS TO DRIVE SAID SEGMENTS AS AN INTEGRATED UNIT ALONG SAID AXIS, EACH OF SAID SEGMENTS EXTENDING DOWNWARD FROM SAID RIGID, COMPOSITE HEAD INDEPENDENTLY AND FREELY OF THE OTHER OF SAID SEGMENTS, SAID DOWNWARD EXTENDING SEGMENTS BEING DISPOSED IN OPPOSED POSITIONS FOR FLEXURAL MOVEMENT BENEATH SAID HEAD RELATIVE TO EACH OTHER AND TO SAID AXIS, AND ACTUATING MEANS INTERMEDIATE SAID SEGMENTS FOR FLEXING SAID SEGMENTS BENEATH SAID RIGID HEAD INTO AND OUT OF ENGAGEMENT WITH A SHELL IN A PATH TRANSVERSE TO THE DRIVING AXIS OF SAID MANDREL. 